JPH0569819A - Brake control device - Google Patents

Abstract

PURPOSE:To cope with the whole of function such as boosting control function, ABS function, TCS function and the like as well as to secure braking performance when pressure is lost from an external pressure source by providing a switching valve which makes switch-over in such a way that control hydraulic pressure is boosted when control hydraulic pressure is built up through an electronic hydraulic pressure control valve, and also makes switch-over in such a way that the pressure of a master cylinder is boosted when no control hydraulic pressure is built up. CONSTITUTION:An electronic hydraulic pressure control valve 5, an electromagnetic switching valve 8 and a hydraulic pressure booster 12 are interposed among a master cylinder 2, an external hydraulic pressure source 7 and respective wheel cylinders 4, so that they are made to cope with the whole of boosting control function, ABS function and TCS function. A control hydraulic oil path 9 from the electromagnetic switching valve 8 is connected to a master cylinder hydraulic oil path 10 and to an input pressure oil path 17, control hydraulic pressure PC is made to act as pilot pressure, when control hydraulic pressure PC is built up, input pressure PIN to a hydraulic booster 12 is made to be control hydraulic pressure PC, and when control hydraulic pressure PC is not built up, a hydraulic switching valve 18 is switched over to turn an input pressure PIN to the hydraulic booster 12 into the pressure of the master cylinder (PM), so that sufficient braking performance is thereby secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for arbitrarily controlling the braking force applied to each wheel regardless of whether or not the brake is operated.

[0002]

2. Description of the Related Art Conventionally, as a brake control device, for example, a device described in Japanese Patent Laid-Open No. 62-149543 is known.

In this conventional source, a modulatable pressure device and a pressure modulator are provided between a master cylinder and a wheel cylinder,
A device capable of receiving a master cylinder pressure and an external pressure to output a desired multiple of the master cylinder pressure in a modulatable pressure device and outputting a brake pressure equivalent to the sum of this pressure and the master cylinder pressure in a pressure modulator is shown. ing.

[0004]

However, the above-mentioned conventional brake control device has a boosting control function for increasing the master cylinder pressure by having a variable pressure regulator and an external hydraulic power source when the brake is not operated. Since it is possible to apply pressure to the wheel cylinders, it is possible to achieve a traction control function (hereinafter referred to as TCS function) that suppresses the drive wheel slip by the braking force when the drive wheel slip occurs, but the pressure loss of the external hydraulic power source occurs. Sometimes, by directly applying the master cylinder pressure to the wheel cylinders, the braking function is guaranteed and safety is ensured even when the pressure of the external hydraulic power source fails, but since the boosting function is lost, emergency braking is possible. Can not exert sufficient braking performance.

The present invention has been made by paying attention to the above-mentioned problems, and in a brake control device for arbitrarily controlling the braking force applied to each wheel regardless of the presence or absence of a brake operation, a boost control function, for example, It is an object to support all of the anti-skid brake function (hereinafter referred to as ABS function), the TCS function, and the like, and to secure sufficient braking performance when the pressure of the external hydraulic power source fails.

[0006]

In order to solve the above problems, in the brake control device of the present invention, the control hydraulic pressure is boosted when the control hydraulic pressure from the electronic hydraulic control valve is generated, and the master cylinder pressure is increased when the control hydraulic pressure is not generated. A switching valve for switching to boost is provided.

That is, as shown in the claim correspondence diagram of FIG. 1, a master cylinder b for generating a master cylinder pressure PM in accordance with an operating force applied to a brake operating means a and a braking device c for each wheel are provided. A wheel cylinder d, an electronic hydraulic control valve f that regulates the hydraulic pressure supplied from an external hydraulic pressure source e using the master cylinder pressure PM as a pilot pressure, and a hydraulic pressure that makes the input pressure of a predetermined pressure a higher wheel cylinder pressure PW. When the control hydraulic pressure is generated from the booster g and the electronic hydraulic control valve f, the input pressure to the hydraulic booster g is set as the control hydraulic pressure PC, and when the control hydraulic pressure is not generated from the electronic hydraulic control valve f, And a switching valve h for switching the input pressure to the hydraulic booster g to the master cylinder pressure PM.

[0008]

In normal braking, the hydraulic pressure supplied from the external hydraulic pressure source e is adjusted to the control hydraulic pressure PC by the electronic hydraulic pressure control valve f with the master cylinder pressure PM generated according to the operating force on the brake operating means a as the pilot pressure. Is pressed. When the control oil pressure PC is generated in this way, the switching valve h is switched to the side where the input pressure to the oil pressure booster g is set as the control oil pressure PC, and therefore the control is performed by the oil pressure booster g. The hydraulic pressure PC is set to a higher wheel cylinder pressure PW and is applied to the wheel cylinders d provided in the braking devices c of the respective wheels. That is, a boosting control function of arbitrarily producing the control hydraulic pressure PC according to the master cylinder pressure PM and increasing the control hydraulic pressure PC is exerted.

For example, when a wheel braking lock is likely to occur due to sudden braking, low μ road braking, or the like, the hydraulic pressure supplied from the external hydraulic power source e according to the slip condition of the wheel is controlled by the electronic hydraulic control valve f. Control hydraulic pressure P for increasing / holding / depressurizing
Pressure is adjusted to C. When the control oil pressure PC is generated in this way, the switching valve h is switched to the side where the input pressure to the oil pressure booster g is set as the control oil pressure PC, so that the oil pressure booster g is used. The wheel cylinder pressure PW is obtained by increasing, maintaining, and reducing pressure corresponding to the control oil pressure PC, and is applied to the wheel cylinders d respectively provided in the braking devices c of the respective wheels. That is, the ABS function for preventing wheel braking lock can be exerted during sudden braking, braking on low μ roads, and the like.

For example, when a drive wheel slip occurs due to a sudden depression of the accelerator or the like, the electronic hydraulic pressure control valve f uses only the hydraulic pressure supplied from the external hydraulic power source e to set a predetermined value according to the occurrence state of the drive wheel slip. The pressure is adjusted to the control oil pressure PC. When the control oil pressure PC is generated in this way, the switching valve h is switched to the side where the input pressure to the oil pressure booster g is set to the control oil pressure PC, and therefore the control is performed by the oil pressure booster g. Wheel cylinder pressure PW with higher hydraulic pressure PC
And is applied to the wheel cylinders d provided in the braking device c of each wheel. That is, the TC that suppresses the drive wheel slip by the braking force when the drive wheel slip occurs
The S function can be exerted.

When the hydraulic pressure is not supplied from the external hydraulic pressure source e and the pressure of the hydraulic pressure source fails, the control hydraulic pressure P by the electronic hydraulic control valve f is generated.
There is no occurrence of C. When the control hydraulic pressure PC is not generated in this way, the switching valve h is switched to the side that uses the master cylinder pressure PM as the input pressure to the hydraulic booster g. The master cylinder pressure PM is set to a higher wheel cylinder pressure PW, which is applied to the wheel cylinders d provided in the braking devices c of the respective wheels. That is, sufficient braking performance is ensured, which has a boosting ability when the hydraulic pressure fails.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

First, the structure will be described.

FIG. 2 is an overall system diagram showing a brake control device according to the first embodiment of the present invention. The first embodiment device has a master cylinder pressure PM according to an operating force applied to a brake pedal 1 (corresponding to a brake operating means). And a wheel cylinder 4 provided in the disc brake device 3 (corresponding to a braking device) of each wheel.
And a master cylinder pressure chamber 50 to which the master cylinder pressure PM is supplied from the master cylinder pressure port 5e. The force by the master cylinder pressure PM is used for the pressure increasing side of the spool 51 and the force by the proportional solenoid 52 is used by the spool 51.
Of the electronic hydraulic control valve 5 used on the depressurizing side, and an input port 5a of the electronic hydraulic control valve 5 via an accumulator pressure oil passage 6 and including an oil pump 7a, a check valve 7b and an accumulator 7c. Hydraulic power source 7,
The TCS port PT of the electronic hydraulic control valve 5 is provided in the branch oil passage 6a of the accumulator pressure oil passage 6, and the TCS pressure PT with the accumulator pressure PS as the base pressure is provided by opening the valve.
The electromagnetic switching valve 8 which acts on the pressure increasing side of the spool 51 via the control valve, and the input pressure PIN due to the control hydraulic pressure PC or the master cylinder pressure PM becomes the high wheel cylinder pressure PW due to the difference in the pressure receiving area of the step plunger 121. The booster 12, the control hydraulic oil passage 9 from the electronic hydraulic control valve 8, the master cylinder pressure oil passage 10 and the input pressure oil passage 17 are connected to operate with the control hydraulic pressure PC as the pilot pressure, and the control hydraulic pressure PC. Is generated, the input pressure P to the hydraulic booster 12 is generated.
IN is the control oil pressure PC, and when the control oil pressure PC is not generated,
An oil passage switching valve 18 (corresponding to a switching valve) for switching the input pressure PIN to the hydraulic booster 12 to the master cylinder pressure PM is provided.

The electronic hydraulic control valve 5 includes a first plunger 5 between the master cylinder pressure chamber 50 and the spool 51.
3, the second plunger 54, the pedestal 55 and the third plunger 56 are arranged, and the valve case 60 and the first plunger 5 are arranged.
The first spring 57 is interposed between the valve case 6 and
A second spring 58 is interposed between 0 and the second plunger 54. The first spring 57 is set to have a higher setting force than the second spring 58. And spool 5
A third spring 59 for pushing the spool 51 rightward in the drawing is provided on the side of the proportional solenoid 52 of No. 1. Further, an output port 5c and a drain port 5d are provided as ports.

The hydraulic booster 12 includes the step plunger 1
A control hydraulic chamber 122 communicating with the input port 12a is formed on the large diameter side of the wheel 21, and a wheel cylinder pressure chamber 123 communicating with the output port 12b is formed on the small diameter side of the stepped plunger 121.
Is formed, and the step plunger 121 is biased in the left direction in the drawing by the return spring 124.

The proportional solenoid 5 of the electronic hydraulic control valve 5
2 and the solenoid 81 of the electromagnetic switching valve 8 are drive-controlled by a command from the brake controller 13, and the brake controller 13 includes a longitudinal acceleration sensor 14, a wheel speed sensor 15, a master cylinder pressure sensor as sensors for obtaining input information. 16 etc. are connected.

That is, the drive control by the brake controller 13 is a boost control for increasing the master cylinder pressure PM, an ABS control for preventing wheel lock during braking, and a TCS control for suppressing drive wheel slip at the time of starting or sudden acceleration. Is performed.

Next, the operation will be described.

(A) During normal braking First, in the electro-hydraulic control valve 5 before the brake operation, the first spring 57 has a higher setting force than the second spring 58. The second plunger 54 is pressed against.

When the brake pedal 1 is stepped on, a master cylinder pressure PM is generated in the master cylinder 2 in accordance with the brake pedal force and is supplied to the master cylinder pressure port 5e of the electronic hydraulic control valve 5, and the master cylinder pressure PM is applied by the brake operation. When PM reaches PM1, the first plunger 53
The force acting on the first spring 57 overcomes the spring force,
The first plunger 53 moves leftward in the drawing.

Therefore, the pressing force of the second plunger 54 to the right is eliminated, and the second plunger 54 moves to the left in the drawing by the force of the master cylinder pressure PM and the second spring 58 to push the pedestal 55, and further the spool. Push 51 to the left in the drawing. The force at that time is the spring force of the second spring 58, which is F2.
And the pressure receiving area of the second plunger 54 is A4, F2
＋ A4 ・ PM.

When a force of (F2 + A4.PM) is applied to the spool 51, the spool 51 moves to the left in the drawing and moves to the port 5
10, the accumulator pressure PS flows from the input port 5a to the output port 5c. Since the spool 51 is a two-stage spool having a step, the output port 5c
The control oil pressure PC causes a force to move the spool 51 to the right. If the large-diameter step area is A1 and the small-diameter cross-sectional area is A2, the force at that time is (A1-A2) · PC.

The balance of the spool 51 at this time is as follows: (A1-A2) .PC = A4.PM + F2-F1 (F1; spring 5
9 spring force).

Therefore, the control oil pressure PC is proportional to the master cylinder pressure PM and is the spring force (F2-F1) added.

Next, when a current is applied to the proportional solenoid 52, a force FS proportional to the current i is applied to the solenoid plunger 61.
Occurs, the spool 51 is pushed rightward in the drawing. The balance of the spool 51 at this time is (A1−A2) · PC = A4 · PM + F2−F1−FS.

Therefore, the control oil pressure PC is controlled to increase or decrease according to the current i to the proportional solenoid 52.

As described above, when the control oil pressure PC is generated in accordance with the brake operation, the oil passage switching valve 18 having the control oil pressure PC as the pilot pressure is connected to the control oil pressure oil passage 9 and the input pressure oil passage 17. The control hydraulic pressure PC is supplied to the hydraulic booster 12 by switching the master cylinder pressure oil passage 10 and the input pressure oil passage 17 to the side where they are cut off.
Move 1 to the right in the drawing. When the step plunger 121 moves to the right in the drawing, the wheel cylinder pressure chamber 123 is pressurized.
The area ratio of 21 (A5 / A6; A5 is a large area, A6 is a small area) is applied.

With the above operation, the wheel cylinder pressure PW
Is controlled by the following equation.

PW = {A5. (A4.PM + F2-F1-FS)} /
{A6 · (A1-A2)} If this is illustrated, the characteristic shown in FIG. 3, that is, when the solenoid current i is zero, the pressure increase ratio becomes the largest, and (a)
When the solenoid current i is increased, the wheel cylinder pressure PW is reduced by an amount proportional to the solenoid current i, resulting in the characteristic (b). Incidentally, FIG.
(C) characteristic is a PM = PW characteristic in which the master cylinder pressure PM is directly used as the wheel cylinder pressure PW.

Therefore, the wheel cylinder pressure characteristic with respect to the master cylinder pressure is set in the brake controller 13 according to the vehicle state by a function or a map, and based on the information indicating the vehicle state and the information from the master cylinder pressure sensor 16. By controlling the solenoid current i, the wheel cylinder pressure can be obtained with an arbitrary boosting characteristic according to the vehicle state. That is, a boost control function having a high degree of freedom is exerted instead of a unique boost ratio.

(B) During ABS operation When wheel locking is likely to occur during sudden braking or low μ road braking, ABS operation for preventing wheel locking by a control command from the ABS control section of the brake controller 13 to the proportional solenoid 52. Is performed.

That is, as the normal boosting characteristic, (a)
By setting the solenoid current i such that an intermediate characteristic between the characteristic and the (b) characteristic is obtained, it is possible to increase the pressure up to the characteristic (a) and reduce the pressure up to the characteristic (b). The slip rate of each wheel is obtained from the vehicle speed information obtained by integrating the input signal from 14 and the wheel speed information obtained from the wheel speed sensor 15 so that the slip rate falls within the range of the optimum slip rate. The cylinder pressure PW can be increased, maintained, or reduced.
During the ABS operation, the oil passage switching valve 18 is controlled by the control oil pressure P.
Due to the generation of C, the control hydraulic oil passage 9 and the input pressure oil passage 17 are communicated with each other, and the master cylinder pressure oil passage 10 and the input pressure oil passage 17 are switched off.

That is, the ABS for improving the vehicle stability during braking.
The function can be achieved with a sufficient increase or decrease of the wheel cylinder pressure PW.

(C) When the TCS is operating When the drive wheel slip occurs due to the sudden accelerator pedal operation at the time of starting or sudden acceleration, the brake controller 13
The TCS operation for suppressing the drive wheel slip is performed by the control command for the proportional solenoid 52 and the ON command for the solenoid 81 from the TCS controller.

That is, when the ON command is output to the solenoid 81, the electromagnetic switching valve 8 is opened,
The accumulator pressure PS is supplied to the TCS port 5b of the electronic hydraulic control valve 5 as the TCS pressure PT.

This TCS pressure PT acts on the third plunger 56 and moves the spool 51 leftward in the drawing. The balance of the spool 51 at this time is (A1−A2) · PC = A3 · PT−F1−FS (A3; pressure receiving area of the third plunger 56).

Therefore, although the master cylinder pressure PM is not generated, the control oil pressure PC changes from the maximum pressure determined by the TCS pressure PT to the pressure obtained by reducing the force FS proportional to the solenoid current i by the solenoid current i. It can be controlled arbitrarily. The characteristic is the characteristic shown in FIG.

That is, the braking force can be applied to the drive wheels in accordance with the amount of the drive wheel slips, and the TCS function of effectively suppressing the drive wheel slips is exhibited.

(D) At the time of failure At the time of failure of the electronic control system associated with the brake controller 13, the current i to the proportional solenoid 52 is set to zero and the electromagnetic opening / closing valve 8 is closed.

Therefore, since the force acting on the spool 51 is (A1−A2) · PC = A4 · PM + F2−F1, ABS operation and TCS operation cannot be performed, but the characteristic (a) of FIG. 3 is retained. To be done.

That is, the state of maximum capacity of the brake boosting performance is ensured, and the braking action having the boosting function is guaranteed.

When the hydraulic source pressure fails such that the accumulator pressure PS is not output from the external hydraulic source 7 due to a failure of the oil pump 7a or the like, the control hydraulic pressure PC is not generated by the electronic hydraulic control valve 5. When the control oil pressure PC is not generated in this way, the oil passage switching valve 18 having the control oil pressure PC as the pilot pressure changes the input pressure to the hydraulic booster 12 to the master cylinder as shown in FIG. The pressure is switched to the side where the pressure is set to PM. Therefore, the master cylinder pressure P is increased by the hydraulic booster 12.
M is set to a higher wheel cylinder pressure PW and is applied to the wheel cylinder 4 of each wheel.

Therefore, when the pressure of the hydraulic power source fails, as shown in the characteristic (b) of FIG. 3, the braking action with the boosting capability is guaranteed.

As described above, in the brake control device of the first embodiment, the effects listed below can be obtained.

(1) In the brake control device for arbitrarily controlling the braking force applied to each wheel regardless of whether or not the brake is operated, between the master cylinder 2 and the external hydraulic power source 7 and the wheel cylinder 4 of each wheel, respectively. Since the electronic hydraulic control valve 5, the electromagnetic switching valve 8 and the hydraulic booster 12 are provided,
It is possible to support all of the boost control function, the ABS function, and the TCS function.

(2) Since the force by the master cylinder pressure PM is used on the pressure increasing side of the spool 51 and the force by the proportional solenoid 52 is used on the pressure reducing side, the electronic hydraulic control valve 5 is used.
When the electronic control system in which the current i to the proportional solenoid 52 is set to zero and the electromagnetic opening / closing valve 8 is closed fails, the state of the maximum capacity of the brake boosting performance is secured, and the braking action having the boosting function can be guaranteed.

(3) The control hydraulic oil passage 9 from the electronic hydraulic control valve 8, the master cylinder pressure oil passage 10 and the input pressure oil passage 17 are connected to operate with the control oil pressure PC as the pilot pressure.
When the control hydraulic pressure PC is generated, the input pressure PIN to the hydraulic booster 12 is set as the control hydraulic pressure PC, and when the control hydraulic pressure PC is not generated, the input pressure PIN to the hydraulic booster 12 is set as the master cylinder pressure PM. Since the oil passage switching valve 18 for switching is provided, it is possible to secure sufficient braking performance having a boosting function when the pressure of the external hydraulic power source 7 fails. As a result, the vehicle can be stopped with high braking performance during emergency braking after the pressure failure of the external hydraulic power source 7 occurs.

Next, the brake control device of the second embodiment will be described.

FIG. 4 is an overall system diagram showing a brake control device according to a second embodiment of the present invention. This second embodiment device is in the middle of an oil passage connecting the master cylinder pressure chamber 50 and the oil passage switching valve 18. The brake fluid separator 19 is provided in the. The brake fluid separator 19 includes a first piston 191 and a second piston 192 that are arranged to face each other with a spring 190 interposed therebetween, an upper fluid chamber 193 on the side of the first piston 191, and a second piston 192.
Side lower liquid chamber 194, the upper liquid chamber 193 communicates with a master cylinder system oil passage 10a communicating with the master cylinder pressure chamber 50, and the lower liquid chamber 194 communicates with an oil passage switching valve 18. Wheel cylinder system oil passage 10b to be connected
Communicate with. Since the other configurations are similar to those of the apparatus of the first embodiment, the corresponding components are designated by the same reference numerals and the description thereof will be omitted.

As for the operation, when the master cylinder pressure PM is generated in the master cylinder 2 due to the brake operation, the master cylinder pressure PM of the master cylinder system oil passage 10a is directly transferred to the wheel cylinder system oil passage via both pistons 191 and 192. 10a, and shows the same operation as that of the first embodiment device. Incidentally, when the master cylinder pressure PM is suddenly increased, the spring 190 is compressed to suppress the rapid increase of the master cylinder pressure PM transmitted to the wheel cylinder system oil passage 10a.

As described above, in the apparatus of the second embodiment, the following effects are added in addition to the effects of (1), (2) and (3) above.

(4) Since the brake fluid separator 19 is provided,
Different brake fluids can be used for the master cylinder system and the wheel cylinder system. As a result, for example, the wheel cylinder system can use power steering oil or the like, and the hydraulic source can be integrated with the hydraulic sources of other hydraulic devices mounted on the vehicle.

Although the embodiment has been described above with reference to the drawings, the specific structure is not limited to this embodiment.

For example, in the embodiment, as the switching valve, the oil passage switching valve 18 that operates using the control oil pressure PC as the pilot pressure is used.
However, an electromagnetic switching valve which detects the control oil pressure PC by a hydraulic pressure sensor and performs switching operation depending on whether PC = 0 or not may be used.

In the embodiment, the proportional solenoid is used as the actuator of the electrohydraulic control valve, but a force motor, a rotary linear conversion type motor or the like may be used.

A pedal depression force sensor of the brake pedal may be used instead of the master cylinder pressure sensor of the embodiment. In this case, since a motor other than the solenoid and a sensor other than the pressure sensor can be used, it is possible to meet various design needs.

It is also possible to control the brake pressure in order to control the turning characteristics of the vehicle by controlling the yaw rate F / B.

[0059]

As described above, according to the present invention, in the brake control device for arbitrarily controlling the braking force applied to each wheel regardless of the presence or absence of the brake operation,
Since a switching valve for boosting the control hydraulic pressure when the control hydraulic pressure is generated from the electronic hydraulic control valve and for switching the master cylinder pressure when the control hydraulic pressure is not generated is provided, the boost control function and, for example, the ABS function and the TCS function are provided. It is possible to obtain an effect that it is possible to secure sufficient braking performance when the pressure of the external hydraulic power source fails, in addition to all of the above.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a brake control device of the present invention.

FIG. 2 is an overall system diagram showing a brake control device according to a first embodiment of the present invention.

FIG. 3 is a diagram showing respective characteristics of a wheel cylinder pressure with respect to a master cylinder pressure in the brake control device of the first embodiment.

FIG. 4 is an overall system diagram showing a brake control device according to a second embodiment of the present invention.

[Explanation of symbols]

 a brake operating means b master cylinder c braking device d wheel cylinder e external hydraulic power source f electronic hydraulic control valve g hydraulic booster h switching valve

Claims (1)

[Claims] 1. A master cylinder that generates a master cylinder pressure according to an operating force applied to a brake operating means, a wheel cylinder provided in a braking device for each wheel, and an external hydraulic power source using the master cylinder pressure as a pilot pressure. An electronic hydraulic control valve that regulates the hydraulic pressure supplied from the hydraulic pressure booster, a hydraulic booster that uses a predetermined input pressure as a higher wheel cylinder pressure, and a hydraulic pressure booster that generates a control hydraulic pressure from the electronic hydraulic control valve. And a switching valve that uses the input pressure to the force booster as the control hydraulic pressure and switches the input pressure to the hydraulic booster to the master cylinder pressure when the control hydraulic pressure from the electronic hydraulic control valve is not generated. A brake control device characterized by the above.